A combination of the world energy crisis and a realisation that greenhouse gases could present a threat to the environment has led to the need for the development of combustion motors which are energy efficient.
Energy efficiency can be achieved in two basic ways. The first of these ways is the obvious one of converting combustion energy efficiently to mechanical energy. A less obvious way is to reduce the weight of combustion engines used to drive vehicles. The weight of the engine is a significant proportion of the overall weight of the vehicle. As fuel consumption is directly related to the vehicle weight, a lighter engine automatically leads to a lighter vehicle and hence reduced fuel consumption.
Thus, in order to maximise energy efficiency, there is a need for the development of engine designs which combine energy efficiency in converting combustion energy to mechanical energy with light weight.